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THE EFFECT OF LED LAMPS’ ULTRAVIOLET RADIATION ON MICROFLORA INDICATORS IN OPEN SPACE OFFICE

THE EFFECT OF LED LAMPS’ ULTRAVIOLET RADIATION ON MICROFLORA INDICATORS IN OPEN SPACE OFFICE

ISSN 2223-6775 Ukrainian journal of occupational health Vol.20, No 3, 2024

https://doi.org/10.33573/ujoh2024.03.184

THE EFFECT OF LED LAMPS’ ULTRAVIOLET RADIATION ON MICROFLORA INDICATORS IN OPEN SPACE OFFICE

Nazarenko V.I.1), Leonov Yu.I.1), Sokurenko S.A.2), Pochta I.V.3), Cherednichenko I.M.1), Kovaleva Yu.V.4), Myshchenko I.5), Brukhno R.P.1)

1) State Institution "Kundiiev Institute of Occupational Health of the National Academy of Medical Sciences of Ukraine", Kyiv

2) "NAFTOGAZ CT" LLC, Kyiv

3) "LED Azimut" LLC, Kamianske. Dnipropetrovsk region

4) NTU "Dniprovska Polytechnic", Dnipro

5)Accredited Laboratory of Occupational Health and Safety, Wroclaw University of Science and Technology, Wroclaw, Poland

Full article (PDF): UKR

Introduction. Any production premises, educational auditorium or office has a constant presence in its air space and on work surfaces of a certain amount of microflora: bacteria, viruses, mold fungi and their spores, which requires the implementation of preventive measures and the reduction of the number of microorganisms, especially, during periods of increased incidence of ARVI. One of the modern non-contact means of indoor air and surface disinfection are modern energy-efficient, ozone-free LED sources of UV radiation with a wavelength of 280 nm, which is represented in the solar spectrum that reaches the Earth's surface.

The aim of the study is to determine the effectiveness of the use of open-type bactericidal ultraviolet monochrome light-emitting diode (LED) lamps for disinfection of work surfaces in an open-type office (Open Space).

Research materials and methods. The studies of the bactericidal efficiency of open-type LED lamps UVC T5-5W-275NM were carried out in a modern open space type office of an enterprise in the oil and gas production industry of Ukraine. The duration of UV exposure was 11 weeks. The contamination of work tables in the office premises by the number of colony-forming units (CFU) per 1 dm2 of surface area was studied before the beginning of exposure and after it ended. The studies were conducted in 3 defined zones of the office premises: near the entrance to the office (zone № 1), the central part (zone №2), the far part - without a UV lamp (№ 3).The swabbing method was used to determine the number of CFUs. The assessment of microbial contamination of indoor space was carried out in accordance with the recommendations of the SBM-2015 standard (Germany).

The results. As a result of the conducted research, it was established that this premises does not contain significant contamination of surfaces with mold fungi - an average of up to 5 CFU/dm2 was found. However, in experimental part 1, the number of CFU of mold fungi was significantly higher, compared to the others. The value of the total number of bacteria reached >100 CFU/dm2 (abnormal contamination). Which indicates significant microbiological contamination. The indicators of the presence of Staphylococcus aureus on table surfaces were also high (on average 40-50 CFU/dm2). As a preventive measure, LED UVC T5-5W-275NM lamps with a wavelength of 280 nm were installed in two parts of the office premises, and the impact of the open-type irradiator system on the number of microorganisms was evaluated.

Conclusions. In a modern office of the open type (Open Space), microbial contamination is found on the surfaces of the work tables from "slight" (up to 20 CFU/dm2) to " extreme anomaly" (> 100 CFU/dm2) degree according to the criteria of the SBM 2015 Guidelines (Germany). At the same time, the microflora is represented by various types of bacteria, a very small number of molds, and the presence of Staphylococcus aureus. The use of LED UVC T5-5W-275NM bactericidal lamps of the open type in the presence of people leads to a decrease in the total microbial contamination of surfaces by almost 3 times or by 4 degrees, according to the criteria of the SBM 2015.

The use of UV LED lamps T5-5W-275NM allows to significantly reduce, by 4 times or by 1-2 degrees, the number of CFU Staphylococcus aureus and not exceeding, at the same time, the limit value of human exposure (30 J/m2). The introduction of modern energy-saving LED sources of bactericidal UV radiation is a promising direction for improving the air in office premises, especially the open space type, where a significant number of employees are located. At the same time, there is a need to develop appropriate hygienic regulations for their use, taking into account the requirements of biological safety in accordance with the Order of the Ministry of Health dated 06.05.2021 No. 882 and DSTU EN 62471:2017 "Safety of lamps and lamp systems photobiological (EN 62471:2008, IDT; IES 62471:2006, MOD)".

Key words: open-type bactericidal ultraviolet monochrome LED lamps, indicators of microflora, open-type office (open space)

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